#define _CRT_SECURE_NO_WARNINGS 1
#include <stdio.h>
int main()
{
	int arr[] = {1,2,3,4,4,5,6};
	int i = 0;
	int sz = sizeof(arr) / sizeof(arr[0]);
	for (i = 0; i < sz; i++)
	{
		if (arr[i] != i + 1)
		{
			printf("%d",arr[i]);
			break;
		}
	}
	return 0;
}